Thermally conductive silicon oxide compositions and their cured forms, and methods of manufacture.

Abstract

A thermally conductive silica composition with excellent preservation, insulation, and thermal conductivity, comprising: (A) an organopolysiloxane; (B) spherical alumina powder with an average sphericity of 0.8 or more, 30 hydroxyl groups / nm² or less, an average particle size of 8 μm or more but less than 50 μm, and coarse particles of 96-150 μm accounting for 0.1-30% by mass of the total of component (B); (C) alumina powder with an average particle size of 0.1-5 μm and an irregular shape; (D) an organopolysiloxane containing at least one silicon group different from component (A) per molecule, and having a viscosity of 0.01-30 Pa·s at 25°C; and (E) an ion scavenger selected from cation exchange and double ion exchange types, comprising 0.01-10 parts by mass relative to 100 parts by mass of component (A); wherein, The volume ratio of the blending ratio of component (B) to component (C) ((B):(C)) is 5:5 to 9.5:0.5.